The present invention relates to a coating and drying device which coats light-sensitive layers on a roll-wound long roll sheet material (hereinafter, referred to as a web) and dries it to manufacture a light-sensitive film, and an ultrasonic wave welding device and splice sensing device which senses splices of aforesaid web.
In continuous production of a light-sensitive film, a web wound on a supply roll on an unwinding device is continuously unwound for production. When one web is totally unwound due to the passage of time, a the leading end of web used for the next production is spliced to the previous web. Incidentally, the roll currently unwinding is referred to as the first supply roll, and the roll used for the next production is referred to as the second supply roll. Webs wound from the first roll and the second roll are respectively referred to as the first web and the second web.
FIG. 18 is a schematic drawing showing a conventional splice sensing method. FIG. 19 is a schematic drawing showing a conventional joining method. In conventional splicing, as shown in FIG. 19, the first web and the second web are cut with an automatic splicer, and then, a wide silver-colored tape strip is sealed in front of and behind the web joint. Aforesaid silver tape portions are, as shown in FIG. 18, sensed as a pulse signal by an electrostatic volume sensor and a converter to control tracking.
However, aforesaid silver tape portion (see FIG. 19) induces air-drag, solution splashing due to the difference of coating effectiveness on the silver tape and on the web and meandering of the web due to less than perfect parallelness. In addition, process contamination due to the adhesive agent of the metallic silver tape also occurs. Due to the occurrence of uneven coating and uneven undrying as a result of the aforesaid issues, acceptable coating is impossible so that much product loss occurs.
In order to overcome aforesaid solution splashing and meandering due to lack of parallelity, it is necessary to smooth the transition of the trailing end of the first web and the leading end of the second web and to minimize the amount of overlap of the first web and the second web. In addition, it is also necessary to weld webs while keeping the welding load constant to assure smoothly joined webs.